Hypoxia-ischemia damages the brain in a developmental stage-specific and region selective manner. Evidence suggests that selective cellular vulnerability contributes to differing patterns of age-related hypoxicic schemic injury. In a rodent model of human periventricular white matter injury, we determined that early hypoxia-ischemia leads to the selective cell death of sub-plate neurons, a cell population unique to the developing brain. Sub-plate neurons are required for activity-dependent formation, refinement and maturation of patterned thalamocortical connections, and may play a role in the unique capacity of the neonatal brain for plasticity during defined critical periods. We have developed a method for purifying sub-plate neurons, representing the first lamina-specific cortical neuronal cultures and have reported the factors that promote sub-plate neuron survival including a novel p75NTR dependent ceramide signaling pathway. Consistent with their selective vulnerability in vivo, cultured sub-plate neurons are more sensitive to oxygen-glucose deprivation than age matched mixed cortical neuronal cultures. Our objectives in this proposal are 1) to determine the significance of selective sub-plate neuron death for subsequent cortical plasticity and 2) utilize purified sub-plate neurons to determine the mechanism of selective sub-plate neuron vulnerability. We hypothesize that selective sub-plate neuron death following early hypoxia-ischemia impairs activity-dependent cortical plasticity. We will quantify activity dependent cortical plasticity following early hypoxia-ischemia and interventions that prevent sub-plate neuron cell death. We hypothesize further that sub-plate neuron selective vulnerability results from altered neurotrophin-mediated p75NTR-dependent signaling and we will investigate this with immunopurified cultures of sub-plate neurons exposed to oxygen glucose deprivation. Finally, we hypothesize that treatments that protect sub-plate neurons in vitro will also prevent sub-plate neuron cell death following early hypoxia ischemia. [unreadable] [unreadable]